Manufacture of alkylated aromatic hydrocarbons



Patented June 8, 1948 MANUFACTURE OF ALKYLATED ABOMATIO HYDROCARBONS Louis Schmcrling and side, lll., assignors Vladimir N. Ipatiefl, Riverto Universal Oil Products Company, Chicago, 111.,

ware

a corporation of Dela- No Drawing. Application April 29, 1943,

Serial No. 485,078 g This case is a continuation-in-part of our application Serial No. 406,408, filed August 11, 1941. now Patent No. 2,375,041, May 1, 1945.

This invention relates to the treatment of aromatic compounds to produce alkylated aromatic compounds.

It is recognized that in general the catalytic alkylation of aromatic compounds has been known \for some time. However, the present invention differentiates from the prior art on this subject in the use of a particular catalytic mate'- rial comprising as its active ingredient cupric orthophosphate or a material formed by calcining cupric orthophosphate at a temperature of from about 200 to about 400 C.

In one broad aspect this invention is concerned with the interaction of aromatic compounds and alkylating agents. By the term "aromatic compound" it is intended to include those compounds having at least one aromatic nucleus such as aromatic hydrocarbons and also the substituted aromatic hydrocarbons particularly phenols, halogenated aromatics and nitroaromatics. As hereinaiter described in greater detail the alleviating agents may comprise oleflnic hydrocarbons, alcohols, alkyl halides, esters, ethers, etc.

In one specific embodiment the present invention comprises a process for producing alkylated aromatics which comprises subjecting an aromatic compound and an allwlating agent to contact under alkylating conditions in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthophosphate.

Aromatic hydrocarbons, such as benzene, toluene, other alkylated benzenes, naphthalene, alkylated naphthalenes, other polynuclear aromatics, etc., which are alkylated as hereinafter set forth, may be obtained by the distillation of coal, by the dehydrogenation of naphthenic hydrocarbons, by the dehydrogenation and cyclization of aliphatic "hydrocarbons, alkylated aromatic hydrocarbons, and alkylated naphthenic hydrocarbons, and by other means.

Oleflnic hydrocarbons utilizable as alkylating agents in the present instance comprise monoolefins and poly-olefins. Olefins which are employed in the present process are either normally gaseous or normally liquid and comprise ethylene and its higher homologues, both gaseous and liquid, the .latter including various polymers of normally gaseous olefins, but these diiferent olefinc hydrocarbons and those mentioned hereinafter are not necessarily equivalent in their action as alkyiating agents. Cyclic olefins may also 11 Claims. (01. 260-624) serve as alkylating agents but generally under conditions diflerent from those employed when.

alkylating aromatic compounds by non-cyclic oleflns, and this reaction may involve intermediate formation oioleflns from cycloparafdns in the presence of the catalyst. Other oleflnic hydrocarbons which may be interacted with aromatic compounds include conjugated diolefins such as butadiene and isoprene, also' non-conjugated dioleflns, and other poly-olefins.

Olefinic hydrocarbons ntilizable as alkylating agents are obtainable from any source and are present in products of thermal and catalytic cracking of oils, in those obtained by dehydrogenating paraflinic and oleflnic hydrocarbons or in the products resulting from dehydrating alcohols.

Aikylation of aromatic compounds may also be effected in the presence of catalysts hereinafter described by charging with the aromatic compound a substance capable of producing oleflnic hydrocarbons under the operating conditions chosen for the reaction. Such olefin-producing substances include alcohols, ethers, esters, and alkyl halides which are capable of undergoing dehydration or splitting to olefinic hydrocarbons, containing at least 2 carbon atoms per molecule, which may be considered as present in the reaction mixture even though possibly only as transient intermediate compounds which react further with the aromatics to produce desired reaction products. It is to be understood that the various alkylating agents are not exact equivalents since different operating conditions may be necessary to obtain optimum results with the different reactants.

Catalysts suitable for use in effecting the procass of the present invention comprise cupric orthophosphate or a material formed by calcining hydrated cupric orthophosphate at a temperature generally within the range utilized in the alleviation reaction namely from about 200 to about 400 C. The hydrated cupric orthophosphate, the corresponding anhydrous salt, or a copper phosphate with an intermediate degree of hydration is utilizable as alkylating catalyst either as such or composited with a carrier such as alumina, silica, silica-alumina composites, diatomaceous earth, crushed porcelain, pumice, firebrick, etc. The addition to the catalyst, before final drying thereof, of free phosphoric acid may increase the alkylatlng activity of the resulting composite catalyst.

A composite catalyst of the type hereinabove described in finely powdered form is thoroughly mixed, then subjected to drying, Pelleting, and heating operations, the latter carried out ina stream of air, nitrogen, or hydrocarbon gases, etc.. to produce formed particles of catalyst suitable for use as packing material in a reactor employed for'eifecting alkylation of aromatic compounds.

' Also, the copper orthophosphate or material formed by calcining this salt may be similarly formed into particles or pellets by compressing a mixture of the powdered catalyst and a suitable pelleting machine lubricant such as hydrogenated cocoanut oil, starch, etc.

The activity of a composite catalyst is controlled to a substantial extent by varying the proportions of active copper phosphate and carrier. Accordingly, catalytic material of appropriate activity is available for use with the more reactive olefins such as those containing a tertiary carbon atom as is present in isobutene, trimethyl ethylene, etc. The different alkylating catalysts which may be thus prepared and employed in the present process are not necessarily equivalent in their action.

Cupric phosphate contains no acidic hydrogen atoms but nevertheless it is an active alkylating catalyst. Although the reactions of this metallic salt are not understood completely, the alkylating activity of copper orthophosphate which contains water of crystallization may be due to partial hydrolysis under operating conditions to produce certain amounts of free phosphoric acid as illustrated by the following equation:

A definite conclusion as to the composition of -the products obtained by calcining cupric phosphate trihydrate can not be made, but a study of analytical results determined thereon indicates that reactions such as the following may also occur when the trihydrate is heated:

The products obtained by heating the trihydrate appeared to consist chiefly of a basic metaphosphate of copper having the same empirical formula as that of cupric pyrophosphate. However, the latter compound as well as the orthophosphate dissolve readily in ammonium hydroxide yielding the deep blue color characteristic of cupric-ammonium compounds, while the calcination product does not dissolve. Thus it is probable that the active ingredient of the alkylating catalyst is not trihydrated cupric phosphate but possibly a partially dehydrated or anhydrous copper phosphate or an acid copper pyrophosphate, the latter formed by reduction of part of the catalyst composite.

In efiecting reaction between aromatic compounds and an alkylating agent, e. g., an oleflnic hydrocarbon, according to the process of the present invention, the exact method of procedure varies with the nature of the reacting constituents. A simple procedure, utiiizable in the case of an aromatic which is normally liquid. or if solid is readily soluble or easily dispersible in a substantially inert liquid, and a normally gaseous or liquid alkylating agent, consists in contacting the aromatic and alkylating agent with a catalyst containing copper orthophosphate or a material formed by calcining copper orthophosphate under the alkylating conditions which comprise a temperature of from about 200 to about 400 C. under a pressure of from substantially atmospheric to approximately atmospheres. Intimate contact of the reacting components with the catalyst is effected by passing the reaction mixture through a fixed bed of granular or pelleted catalyst or the reacting componentsmay be mixed with finely divided catalyst and reacted in either a batch or continuous type of operation. The materials subjected to reaction are preferably in the proportion of 1 molecular proportion of alkylating agent to between about 2 and about 20 molecular proportions of aromatic compound in order to diminish side reactions, e. g., polymerization of olefinic hydrocarbons, and to favor interaction of alkylating agent with the aromatic compound or mixture of aromatic compounds in the fraction undergoing treatment.

Thus, a hydrocarbon mixture comprising essentially normally liquid aromatic hydrocarbons and a fraction containing oleflnic hydrocarbons are commingled and passed through a reactor containing a catalyst as herein described, or at least a portion of the aromatic hydrocarbon is charged to such a reactor while the fraction containing oleflnic hydrocarbons, as such or preferably diluted by another portion of the aromatic hydrocarbon being treated, is introduced at'various points between the inlet and the outlet of the reaction zone in such a way that the reaction mixture being contacted with the catalyst will at all times contain a relatively low proportion of the olefinic hydrocarbon and thus favor interaction of aromatic and olefinic hydrocarbons rather than polymerization of the latter.

While the method of passing the aromatic and alleviating agent, either together or countercurrentiy, through a suitable reactor containing the granular catalyst is generally customary procedure, the interaction of these materials may also be effected in a closed vessel in which some of the reacting constituents are in liquid phase and in which the catalyst is preferably in finely divided form and is maintained in dispersion or suspension by some method of agitation. The choice of operating procedure is dependent upon the circumstances such as the temperature, pressure, and activity of catalyst found to be most effective for producing the desired reaction.

Copper phosphate-containing catalysts as herein described are preferred because they permit continuous reaction in the presence of a fixed bed of catalyst and thus make it possible to avoid mechanical problems as well as oxidation and corrosion difficulties encountered when this reaction is carried out in the presence of sulfuric acid which is sometimes used as an alkylating catalyst. Further, a catalyst of the described type also has the advantage over aluminum chloride utilized as catalyst for alkylating aromatic compounds with oleflnic hydrocarbons in that the copper phosphate-containing catalyst forms substantially no addition compounds or complexes with aromatic and/or oleflnic hydrocarbons as is characteristic of catalysts containing aluminum chloride.

Reactions between aromatic compounds and olefinic hydrocarbons in the presence of the herein described catalysts are apparently of a relatively simple character, although they may be accompanied by certain amounts of polymerization and decomposition. While not understood completely, a typical alkylation of an aromatic compound by an olefln apparently involves the addition 01' the aromatic compound to a double bond of an olefinic hydrocarbon to produce a higher-boiling alkylated aromatic compound which may in turn undergo further reaction with one or more molecular proportions of olefinic hydrocarbons to form dialkylated and more-highly alkylated aromatic compounds. In case the alkylating olefinic hydrocarbon is a diolefln or other poly-olefin containing more than one double bond per molecule, the interaction with an aromatic compound may involve not only the combination of aromatic compound and olefinic hydrocarbons but possibly the polymerization of a higher boiling unsaturated aromatic hydrocarbon resulting from the primary reaction. Thus benzene and 1,3-butadiene give, among other products, a substantial yield of phenyl butene which polymerizes to form dimers of phenyl butene. Within certain limits it is possible to produce mainly mono-alkylated aromatic compounds by proper adjustment of catalyst activity, ratio of the aromatic to the olefinic hydrocarbons charged, operating conditions such as temperature, pressure, and rate of feed of the reacting components, etc.

The reaction between an aromatic compound and a hexene or other normally liquid olefin of higher molecular weight may involve not only addition of aromatic compounds and olefinic hydrocarbons but alsoa depolymerization or splitting of the olefinic hydrocarbon into olefinic fragments of lower molecular weights which react with the aromatic compounds. Thus benzene and di-isobutene or tri-isobutene react and yield tertiary butyl benzene and poly-tertiary butyl benzenes, while nonene and benzene yield both butyl and amyl benzenes as well as other products by so-called depoly-alkylation.

In general, the products formed by interaction of an alkylating agent with a, molal excess of an aromatic compound are separated from the unreacted aromatic by suitable means as by distillation, and the unreacted portion of the aromatic compound originally charged and generally the poly-alkylated aromatics formed are recycled to the process. This recycling of poly-alkylated aromatics sometimes aids in the production of mainly mono-alkylated aromatics and depresses the formation of more-highly alkylated derivatives. The total alkylated product thus freed from the excess of the originally charged aromatic is separated into desired fractions by distillation at ordinary or reduced pressure or by other suitable means.

The presence in the reaction mixture of large amounts of hydrogen is generally not desirable particularly when operating under a relatively high temperature and pressure within the indicated ranges because of the fact that cupric phosphate undergoes hydrogenation to form free copper and phosphoric acid. Thus when 50 parts by weight of cupric orthophosphate trihydrate was heated at 350 C. for 4 hours in the presence of hydrogen under a maximum pressure of 182 atmospheres, there was obtained a copper sponge containing phosphoric acid. By washing the copper'sponge with water and titrating the washings 21.8 parts by weight of phosphoric acid was found which corresponded quite closely to the theoretical yield of 22.6 parts by weight.

The following examples are given to illustrate the character of results obtainable by the use of the present process, although the examples given are not introduced with the intention of unduly restricting the generally broad scope of the inants and catalyst was maintained at 350 C.

vention.

Example I The catalyst used in this experiment was prepared by heating Cus(PO4) 2.3H2O at 300-320" C. for 16 hours.

Approximately 5 grams of this catalyst was charged to a glass lined rotating autoclave of the Ipatieff type along with grams of benzene and 30 grams of ethyl alcohol. The mixture of reactior 4 hours. At the end of this time an analysis of the products showed 4 grams of ethylbenzene and 9 grams of polyethylated benzene. Substantial amounts of ethylene and water were also recovered.

Example II Example I I I In this experiment 5 grams of a catalyst prepared as in Example I was contacted with 60 grams of mono chlorobenzene and 21 grams of propylene in a rotating autoclave at 350 C. After a reaction timeof 4 hours the products were recovered and were, found to contain 14 grams of chloro isopropyl benzene. In addition 7 grams of higher molecular weight alkylated aromatic was recovered.

Example IV Using a catalyst prepared according to Example I and the same equipment described therein, 40 grams of phenol was reacted with 30 grams of isopropyl alcohol in the presence of 5 grams of catalyst at 325 C. After a reaction time of 4 hours the products were analyzed and found to contain 2 grams of isopropyl penyl ether, 8 grams of isopropyl phenol and 6 grams of higher molecular weight alkyl phenols. A small amount of an alkylated isopropyl phenyl ether was also isolated.

Under similar conditions phenol is readily alkylated with olefinic hydrocarbons such as propylene, butylene, etc.

We claim as our invention:

1. A process for the alkylation of an aromatic compound containing at least one nuclear hydro gen atom and selected from the group consisting of phenols, halogenated aromatic hydrocarbons and nitroaromatic hydrocarbons, which comprises reacting said compound with an alkylating agent in the presence of a catalyst containing as its active ingredient a material formed by calcinin cupric orthophosphate.

2. The process of claim 1 wherein said alkylation reaction is conducted at a temperature of from about 200 C. to about 400 C.

3. The process of claim 1 wherein said alkylation reaction is conducted at a temperature of from about 200 C. to about 400 C. under a pressure of from substantially atmospheric to' from about 200 C. to about 400 C. under a presacting phenol with an alkylating agent in the presence of a catalyst containing as its active 11. An alkylation process which comprises reacting a phenol with an alkylating agent in the preseng or a catalyst containing as its active 1 5 orthophosphate.

ingredient a material formed by calcining cupric orthophosphate.

6. The process of claim 5 wherein said alkylating agent comprises an olefine hydrocarbon.

7. The process of claim 5 wherein said alkylating agent comprises an alcohol.

8. An alkylation process which comprises re- 7 acting a halogenated aromatic hydrocarbon containing at least one nuclear hydrogen atom with an alkylating agent in the presence of a catalyst containing as its active ingredient a material formed by calcining cupric orthopfiosphate.

9. The process of claim 8 wherein said alkylating agent comprses an olefinic hydrocarbon.

10. The process of claim 8 wherein said alkylating agent comprises an alcohol.

ingredients 9. material formed by calcining cupric LOUIS BOWLING. VLADIMIR N. IPATIEFF.

REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS Number Name Date 2,140,782 Arnold et al. Dec. 20, 1938 2,183,552 Dreisbach et a1. Dec. 19; 1939' 2,246,762 I Schirm L June 24, 1941 2,290,211 Schaad July 21, 1942 2,301,966 Michel et al Nov. 17, 1942 FOREIGN PATENTS Number Country Date 464,752 Great Britain Apr. 19, 1937 

